Time switch



ug. 1E, 1939 Filed July 1'? g QHRENEDER TRAE SWITCH 3 Sheets-Sheet 1Allg' l5, 1939 K. oHRENEDr-:R 2,169,924

TIME SWITCH Filed July 17, 1936 3 Sheets-Sheet 2 Aug. 15, 1939 K.-oHRENEDr-:R 2,169,924

TIME SWITCH Filed July 17, 1936 3 Sheets-Sheet 3 Patented Aug. 15, 1939UNITED STATES PATENT orifice Application July 17, 1936, SerialNo. 91,246In Austria July 22, 1935 1s claim (Ci. zoo-3a) This invention relates toan electric time switch consisting of a running gearing, clockwork,electromotor, synchronous motor or the like, housed in a casing in whichswitching-on, switching-ofi or both is or are effected at predeterminedtimes .set by turning a rotary ring pertaining to said casing andadapted to actuate means for operating the switch contact.

According to the present invention, in an electric time switch of thiskind, the contact-operating means are independent oi the rotary casingring and are set by a setting device carried by said ring.

The time switch according to the invention is intended to serve moreparticularly for the automatic switching on and on oi' wireless sets andother electrical appliances used in households, for example, electricheating pads or cookers, and is therefore destined for operation as arule by persons devoid of any specialized knowledge' or experience of atechnical nature. In development of this device, therefore, particularattention has been paid to providing for simple and readilyunderstandable manipulation. and to sturdlness of construction.

Forms of construction embodying the inveni tion are shown, by way ofexample, in the accompanying drawings, in which:

Fig. 1 is a side elevation of the time switch according to theinvention.

Fig. 2'shows the same partly in longitudinal section and partly in sideelevation.

Fig. 3 is a plan view with the dial removed.

Fig. 4 is a partial section of the time switch on an enlarged scale.

Fig. 5 shows, in plan view, the part of the mechanism operating thecontacting means in a modified form of construction. y

Fig. 6 is a. plan view e2" the mechanism of this modified form ofconstruction, with the dial-plate removed.

Fig. 7 is a partial longitudinal modied form of construction.

Referring to the drawings, the casing of the instrument consists of thelower 'part I which section of this houses the clockwork mechanism andthe switching mechanism, and of the annular upper part 2 which isrotatably mounted on the lower part and intended to serve for theadjustment of the switching time. Within an annular aperture coveredover by a glass window 3 there is provided the dial-plate 4. 'Iheoutward procedure in setting the instrument to effect a switchingoperation at a certain time is to turn the setting ring a mark 5 on theinside registers with the desired time on the dial, and then to x thesety ting by depressing a button 6.

The switch proper is mounted on a disc I which fast on the journal l ofthe hour hand, and consists of two pairs of tongues 9 to which members.

the current is supplied through slip rings on the under side of thedisc 1. The tongues of each pair press resiliently against each otherand are fitted at their free ends'with contacts. 'Ihese contacts consistpreferably of two doubly tapered, mutually opposed contact members IIImade from precious metal between-which, when the current circuit isinterrupted, there is thrust an insulating knife 45 which separates thetwo tapered This knife is pivoted about an axle II secured to a lug I2on the disc Landis forced by a spring I3 between the contacts. When theknife is deflected against the action of the spring. in the direction o!the arrow I4, the contact members Il are free to come togetlnr under theinfluence of the inherent resilience of the tongues which carry them,and thus close the current circuit. What is intended is to bring aboutthis deflection of lthe pivoted knife automatically by means of theself-contained clock at a pre-determinable time. For this purpose thereis associated with the outwardly projecting abutment I5whichg-.Heilraentlre switch, revolves with the hour 'and which occupiesits extreme position when the knife is in the position in' which it isshown in Fig. 3. Ii' there be interposed in the path of this abutment acounter abutment I6 the abutment I5, which takes the form of alever'arm,yields as it goes past its counter abutment, and thereby swings theswitch blade in the 'direction indicated by the arrow I4, so that theblade is withdrawn from between the contacts, and the circuit becomesclosed in consequence of the spring action of the tongues. Thedeflection of the contact separating blade is eii'ected against theaction of the spring I3, so that this spring becomes tensioned. When thelever arm I5 (Fig. 4) slides clear o! its counter abutment theseparating blade 45 is thrust between the contacts by the action of thespring, l and. in view of its sharrknife-like edge, sepai rates thecontacts instantaneously without allowina an electric arc tobecomforrned.

'I'he position oi the counterabutment I6 relatively to the dial-plate ofthe clock determines, the moment at which the switching-on orcircuitclosing is eiected. If it is desired to be able to set this time,to within intervals of live minutes thereV are required twelve counterabutments for everyhour, that is to say one hundred and fortyfourcounter abutments for a complete revolt;` V

tion of the hour wheel, capable of selectively into the path of movementofthe'abutment I5. The moving up oi' the requiredcounter abutment istobe eiected by means of a setting member associated with the casing ring2. This setting member of a thrust rod I'I which is iitted with a knobi, and which extends Athrough the annular wall into the interior of thecasing, and adapted to co-act with a one-armed lever Il pivotallymounted in the wall of the casing. When pressure is exerted upon theknob B the lever I8 is pivotally swung, against the action of arestoring spring I9, into the interior of the casing. During thismovement its end encounters the head of a rocking lever 20 pivotallymounted in the lower part of the casing, and presses this lever likewiseinto the interior of the casing. The foot of the rocking lever, throughwhich the pivot pin 21 passes, is provided with a notch 2| into which,when the rocking lever is in the position of readiness, there snaps aspur 22 of a spring 23. If on the other hand the rocking lever be tiltedfrom the position of readiness into the interior of the casing bypressure exerted upon the knob 6 the spur 22 comes out of engagementwith the notch 23 and bears against the solid part 24 of the foot. Atthe same time the portion of the spring comprising the spur is forcedinto the interior of the casing. The free end of the spring islengthened to form a tongue which constitutes the counter abutment I6for the stop I5 pertaining to the contact separating blade. By operationof the rocking lever 2U the counter abutment I6 is forced with thespring 23 into the interior of the casing and into the path of movementof the stop I5, and thus operates the switch in the manner alreadydescribed. When once the abutment I5 and the counter abutment havepassed each other the rocking lever must be restored automatically intothe position of readiness. This purpose is served by a spring stop 25which is attached to the lug I2 on the disc 1,

Vand which exerts a directly restoring action upon the deflected rockinglever 20. It will be clear v ,that to each of the one hundred andforty-four 'abutmentsfl' there is allotted a separate rocking lever..

Whenvysettingthe'pointers to the required time it often happens that'thepointers have to be moved in opposite directions. The abutment arm I5associated with the contact separating blade must therefore be so madethat when the pointers are turned back this arm can move past itscounter abutment I6 without actuating the conwhich can be deected in theother direction against the action of a restoring spring 4l. If

. the pawl be moved past the counter abutment I6 in a clockwisedirection it strikes against the peg and is rigidly arrested, so thatwhen slipping clear it takes the contact separating bladgw'ith it.However when the vpawl is moved past the abutment in the oppositedirection it gives way while the restoring spring 4I is tensioned. Therocking levers can thus be turned into the position of readiness evenwhen the marks or pointers are turned backwards. The spring stop 25 isfurnished with two symmetrical running on surfaces of which always thatcorresponding to the direction of rotation for the moment takes effect.

By means of this stop any number of rocking levers situated in thearresting position can be restoredinto the position ofreadiness by asingle complete revolution of the hour hand.

Since the clock switches of the type contemplated by the presentinvention have to `be capable of being manufactured on mass productionlines the assembly must be extremely simple while at the sametimeensuring a' high degree of accuracy. In order that these needs maybe met there are impressed in the annular shoulder or step in the lowerpart of the casing radial slots 20 are threaded. The ribs 28 which areleft standing between the slots are provided at their upper side withgrooves 29 which together constitute a row of grooves which isconcentric to the casing as a whole, and into this row of grooves thewire ring 21 is fitted and there held in position by means of clampingor holding members.

The springs 23 which carry the abutment IIi at their upper end arelikewise fitted into the slots 26 and bear at one end against a ring 30which is inserted in the casing, and which covers the open sides of theslots at the inner delimiting surface of the ribbed member. The springs23 may also be provided on a communal, annular carrier with which theyare integrally formed from a single piece of material. Y

The lower part of the casing comprising the ribbed member is preferablymanufactured in one piece from insulating material, since in this mannerfreedom from short-circuiting and uniformly accurate production isensured.

The upper ends of the rocking levers 20 are guided in radial slots 3l inan annular plate 32 whchis fitted into a groove 33 in the upper endsurface of the lower part of the casing. The free inner surface of thering is lled out bythe dialplate 4. The head of the rocking levers 20 isprovided With extensions 35 pointing towards the interior of the casing,with which it overlaps the dial-plate when rocked out of the position ofreadiness, so that when rocked out it is visible from the outsideagainst the dial-plate, and the time for which the switching'operationis set to take place can'be checked off.

The rocking levers 20 must move easily in their slots, and they aretherefore fitted with slight play. This play makes it diicult however toiit the annular plate 32 in position, since the rocking. levers do notthen all coincide simultaneously with their appropriate slots in theannular plate. In order to overcome thisvdiiculty there arey pressedvinto the upper edge of the lower part of the casing notches whichcentre the rocking levers in the position of readiness.

If it is desired, for example, to switch on a wireless set at a certaintime by means of the clock switch the mark 5 on the setting ring 2 isset to the point on the dial-plate corresponding to the desired timewhile at the same time pressure is exerted upon the knob 6 which tiltsout the rocking lever corresponding to the setting concerned. Theextension 35 on the tilted lever is thereby rendered visible above thedial-plate. The setting operation can be facilitated by providing in theouter shell of the lower part of the casing detent notches 36corresponding to the rocking levers, into which a spring 31 attached tothe inside of the setting ring comes into snap engagement.

The spring is held in position by an angle member 42 which engages withone limb in a groove 43 in the outside ofthe lower part of the casing,thereby preventing withdrawal of the casing ring.

The apparatus will be switched on atthe time the instrument effectswitching off automatically at a later time the setting ring must beused to tilt out all the rocking levers situated between the time atwhich the switching on operation is to be performed and that at whichthe switching oil' operation is desired to be performed.

. Provision must also be made for the restoring into the position ofreadiness of any rocking levers which may happen to be tilted out bymistake. For this purpose there is mounted on the pivot pin for theone-armed lever I8 a bell-crank lever 44 which bears with one limb onthe upper side of the lever `I8 and with the other limb extends into theinterior of the casing. If the rod I1 be then withdrawn from the casingby a pull exerted on the knob 6 the lever I8 also rotates the bellcranklever 44, and thelimb of the latter which projects into the 4interior ofthe casing presses the rocking lever 20 back into its position ofreadiness.

In the form of construction described hitherto each tripped rockinglever brings about a switching operation lasting for a certain lengthofl time which is dependent on the number of rocking levers provided. Ifthere be provided a hundred and forty-four rocking levers in the case oian instrument with a twelve-hour range each rocking lever, when tripped,initiates a switching operation lasting for ve minutes. vThus if it isdesired to make the switching operation last for an hour it is necessaryto trip twelve consecutive rocking levers. In a modified form ofconstruction of the invention, shown in Figs. 5-7 of the accompanyingdrawings, theV number of rocking levers requiring to be tripped in orderto effect a protracted switching operation of any desired duration isreduced to two by virtue of the arrangement that the contacting vmeanslare changed over by each consecutive tripped .rocking lever into theswitching condition which is the reverse of the previous.

Figs. 5 to '7 show a modied device for actuating the Contact structureof the time switch of this invention. Inthis modified device, thecontact structure is not on a disc which rotates with the shaft of thehour hand, but it is stationary, and hence, slip rings which act asconnecting element between the supply of current and the contactstructure may be eliminiated. For operating the contact structure inthis modication, there is provided a stationary spring motor which isreleased or tripped by the stop element that has been set for thedesired time. The release or trip is effected through intermediateelements. The transmitting elementsbetween spring motor arid contactdevice, on the other hand, are of such construction that with each twosuccessive releases by a stop moved to operative position, the contactstructure is alternately switched into and out of the circuit. Takingfor instance a selected current supply period of one hour in the timebetween eleven and twelve oclock, Ait is, therefore, only necessary toset the two stops corresponding to the time 11 oclock and twelve oclockon the dial. K

The spring motor 48 which is supported stationarily, Figs. 5 and 6,operates through a gear transmission illustrated in the drawings thenoncircular disc 5I unless o f course this spring motor is arrested.This non-circular disc 5I carries a cam 52 of approximatelysemi-circular shape.

AUpon rotation of the disc, this cam 52 acts on the lever 53 undercontrol of the spring 54, and thereby moves the separator blade 55 withrespect to the pairs of contacts 55. The separator-.bladey 55 is made ofinsulating material, andt is moved by being positioned alternatelybetween the contact pairs 56 and then back again, overcoming the actionof the spring 54. When the contact pairs 56 are in closed condition, thespring motor 46 is. stopped owing to the lock lever 49 which engages thepin 48 and thereby prevents rotation of the disc 41,'which disc isconnected with the gearing. The release of the lock lever 49 against theaction of its spring 50 to effect interruption of the circuit at apredetermined point of time takesv place in the following way, while atthe same time then moving the separator blade 55 in between the pairs ofcontact 56.

When the stop 20 is moved to operative position`v Fig. 6, a bell cranklever 60 is moved inwardly. This bell crank lever is pivoted on the arm59, which arm is xedly connected with the shaft of an hour hand androtates with said hand. When the bell crank lever 50 has been movedinwardly, it engages at its end which is constructed as a pawl, thecircumference of the star disc 51 which is loose on the shaft 8. Thispawl, therefore, will rotate this disc as long as the engagement betweenthe pawl and the stop 20 is continued. The star disc-51 is, therefore,rotatedfoi this short period of time, and this disc carries along thepin 58 which is fixed to the lock lever 49 and which projects into anaperture of the disc. The disc thereby effects a'rotation of the locklever 49 about its axis in a `direction counterclockwise, whereby thefree end of the lock lever slips oil' the bolt or pin 48. In this mannerthe spring motor 46 is released, and this spring motor imparts rotationto the disc 41 until the lever 49 again engages a pin :65 which isradially farther outward on thedisc 41 than the pin 48. .At the sametime, however, the lever vhas left the stop 25, whereby the pawlengagement of arm 59 with the star disc 51 induced by thel lever 80 hasbeen released. The locking lever 49 then continues its rotation underthe action ofits return spring 50 in clockwise direction untiliitengages the elongated lat portion of the non-circular disc 5| andthereby brings about a return rotation of the star disc 51 by means ofthe pin 5B. Simultaneously the spring motor 46 which is now releasedalso rotates the disc 5I so that the free end of the bell crank 53 aftera rotation of this disc over 180 degrees slips ofi' the circular cam 52and spring 54 of the bell crank lever 53, pushes the separator blade 55between the pairs of contact 56 so as to interrupt thecircuit which hadbeen closed heretofore.

Uponturning the non-circular disc 5|, it acts upon the long arm of thelocking lever 49 when engaging said lever by means of the arcuate edgeportion of the disc 5l. The locking lever 49 is thereby pushed outwardlyso that its free end is beyond the path described by the stop pins 48and 55. Upon continuing the rotation of disc 5l, the

lever 49 engages the second flat portion of the disc and its free endthereby Yenters again into the path of the .pin 48 so that the springmotor is locked again. `The separator bade of the contact -maticallybythe bell-crank lever Y60 when the latter is continued in its movementby the arm 59. Care must be taken in this connection to ensure that theresistance oiieredby the rocking levers '20 to the restoring movement begreater than the resistanceV offered by the jagged wheel to theinitiation of the switching operation.

It is also often of advantage to arrange for an acoustic signal to begiven during the carrying out of the switching operation. For thispurpose sound-giving mechanism consisting of the hammer 62 and bell 63may be operated by a wheel 6l attached to thejournal of the disc 41. Atime switch equipped in this manner can be used for .example as analarm-clock without being connected to any source of current.

The condition of the switching means at any one time can be seen bylookingthrough an inspection aperture in the dial-plate at a mark 64mounted on the contact separating blade and moved simultaneouslytherewith. If this mark is visible through the inspection aperture inthe dial-plate then this means that the contacts are closed.

The dial-plate itself is preferably made lndependent of the ring 32comprising the radial slot guides 3l for the rocking levers 20, so thatthe clockwork together with the dial can be dismantled bodily without atthe same time having to remove the guide ring also, this latter partbeing tedious to fit, since to do so it is rst necessary to insert allvthe rocking levers in their appropriate slots. l

I claim: Y

1. In a time switch, a casing, a power applying mechanism housed by saidcasing, a switchmech# anism within the casing for opening and closing anelectrical circuit, and including a movable contact controlling member,elements in the casing for effecting' actuation of said controllingmember when said elements are set to their operative positions, a'rotatable ring carried by the casing, and means carried by the ring andbrought into operative relation with a selected element by turning thering, for setting the said selected element to its operative position.

2. In a time switch, a casing, a power applying mechanism housed by saidcasing, a switch mechanism within the casing for opening and closing anelectrical circuit, and including a movable contact controlling member,elements in the casing for eiecting actuation of said controlling memberwhen said elements are set to their operative positions, a rotatablering carried by the casing, and means carried by the ring Vand broughtinto operative relation with a selected element by turning the ring, forsetting the said selected element to its operative position, said ringconstituting a part of said casing.

3. Ina time switch, a casing, a power applying mechanism housed by saidcasing, a switch mechanism within the easing for opening and closing anelectrical circuit, and including a movable contact controlling member,elements in the casing for eilecting actuation of said controllingmember when said elements are set to their operative positions, arotatable ring carried by the casing,

4means carried by the'ring and brought into opertive relation with aselected element by turn-- ing the ring, for setting the said selectedelement toits operative position, and means actuated by saidpower-applying means for` restoring said selected element andswitch-controlling member to their initial positions.

4. In a time switch, a casing, a motor 'carried by the easing, arotatable disc within the casing and operated by said motor, a make andbreak switch -carriedby said disc, and including pairs of engagingcontacts and a contact separating device, a set of rocking lever devicesfor eecting actuation of said contact separating device .to release thecontacts to close a circuit, means normally holding said lever devicesinactive, means to set selected lever devices to active position, saidsetting means including a rotatable ring carried by the casing and amanually operated lever-device setting element carried by said ring.

5. In a time switch, a casing, a motor carried by the casing, arotatable disc within the casing and operated by said motor, a make andbreak switch carried by said disc, and including pairs of engagingcontacts and a contact separating device, a set of rocking lever devicesfor effecting actuation of said contact separating device to releasethev contacts to close a circuit, means normally holding said leverdevices inactive, means to set selected lever devices to activeposition, said setting means including a rotatable ring ,carried by thecasing and a manually operated lever-device setting element carried bysaid ring, and means carried by said rotatable disc for re storing saidrocking lever devices to their normal positions and moving said blade toopen-circuit y position.

6. In a time switch, a rotatable disc, pairs of switch contacts on saiddisc, means on said disc -ior normally holding said contacts in oneposition, means to rotate said disc at constant speed, a casingenclosing the aforesaid parts, said casing having radially disposedslots, rocking lever devices held in said slots for controlling thecontact holding means, a rotatable ring forming part. of said casing,means carried by said ring to set said lever devices to operativeposition, and means actuated by rotation of said disc for restoring saidlever devices to normal position after a timed interval.

7. In a time switch, a rotatable disc, pairs of switch contacts on saiddisc, means on said disc for normally holding said contacts in oneposition, means to rotate said disc at constant speed, a casingenclosing the aforesaid parts, said casing having radially disposedslots,v rocking lever devices held in said slots for controlling thecontact holding means, a rotatable ring forming part of said casing,means carried by said ring to set said lever devices to operativeposition, means actuated by rotation of said discfor restoring saidlever devicesto normal position after a timed interval, and anon-rotatable disc in said casing having guide slots for said rockinglever devices.

8. In a time switch, a rotatable disc, pairs of switch contacts on saiddisc, means on said disc for normally holding said contacts in `oneposi- ,tion, means to rotate said disc at constant speed,

`ring comprising a manually actuated setting member for engaging anyrocking lever device into alignment with which said setting member isbrought by rotation of said ring. A

9. In a time switch, a rotatable disc, pairs of switch contacts on saidldisc, means on said disc for normally holding said contacts in oneposition, means to rotate said disc at onstant speed, a casing enclosingthe aforesaid parts, said casing having radially disposed'slots, rockinglever devices held in said slots for controlling the contact holdingmeans, a rotatable ring forming part of said casing, means carried bysaid ring to set said lever devices to operative position, and

means actuated by rotation of said disc for restoring said lever devicesto normal position after a timed interval, said rocking lever devicesincluding rocking levers and spring means to retain said levers ineither of their normal and set positions,

l0. In a time switch, a rotatable disc, pairs of switch contacts on saiddisc, means on said disc for normally holding said contacts in oneposition, means to rotate said disc at constant speed, a casingenclosing the aforesaid parts, said casing havingr radially disposedslots, rocking lever devices held in said slots for controlling thecontact holding means, a rotatable ring forming part of said casing,means carried by said ring to set said lever devices to operativeposition, and means actuated by rotation of said disc for restoring saidlever devices to normal position after a timed interval, said rockinglever devices including rocking levers and spring means to retain saidlevers in either of their normal and set positions, said spring meansincluding a communal annular carrier having individual spring fingers, vi one for each rocking lever.

l1. In a time switch, a casing, a disc rotatable in the casing, means torotate said disc at uniform speed, a switch device carried by said discand including a movable switch opening and lclosin the casing, means torotate said disc at uniform speed, a switch device carried by said discand including a movable switch opening and closing member, a set ofrocking levers mounted in the casing around but separate from said disc,said switch device opening and closing member including aone-way-operating abutment,I a counter-abutment for each rocking lever,means to set a selected rocking lever and its counter-abutment intooperative positions to actuate said oneway-operating abutment, arotatable body carried by said casing and carrying said setting means,and means carried by said disc and operable when said disc is turnedeither way for restoring said rocking levers and counter-abutments tonormal position.

13. In a time switch, a casing, a disc rotatable in the casing, means torotate said disc at uniform speed, a switch device carried by said discand including a movable switch opening and closing member, a set ofrocking levers mounted in the casing around but separate from said disc,said switch device opening and closing member including aone-way-operating abutment, a counter-abutment for each rocking lever,means to' set a selected rocking leyer and its counter-abutment intooperative positions to actuate said oneway-operating abutment, and meanscooperating with said setting means for also restoring the rockinglevers to normal when desired.

14. In a time switch, a casing, a disc rotatable in the casing, means torotate said disc at uniform speed, a switch device carried by said discand including a movable switch opening and closing member, a set ofrocking ievers mounted in the casing around but separate from said disc,said switch device opening and closing member including aone-way-operating abutment, a counter-abutment for each rocking lever,means to set a selected rocking lever and its counter-abutment intooperative positions to actuate said oneway-operating abutment, saidcasing having a sight opening, a dial plate visible through said openingsaid rocking levers each having a projection to cooperate with said dialplate and be visible through said opening when the lever has been set tooperative position.

15. In a time switch, a casing, a disc rotatable in the casing, means torotate said disc at unlform speed, a. switch device carried by said discand including a movable switch opening and closing member, a set ofrocking levers mounted in the casing around but separate from said discsaid switch device opening and closing member including an operatingabutment, a counter-abutment for each rocking lever, means to set aselected rocking lever and its counter-abutment into operative positionsto actuate said operating abutment, said casing including a relativelystationary annular part and a rotatable annular part, said setting meansbeing carried by said rotatable part, said stationary annular parthaving detent notches corresponding to the rocking levers, and a springretaining device carried by said rotatable annular part to snap intosaid detent notches.

16. In a time switch, a casing, a switch mechanism in said casing, meanscarrying said mechanism in a path about an axis, said mechanismincluding a make and break element, means for shifting said element frommake to break positions and from break to make positions, said shiftingmeans including'a set of rocking levers, a device having means'to engagesaid rocking 1evers to actuate said make and break element alternatelyto open and close the switch, and manually operated means to set saidrocking levers to be engaged by said engaging means.

17. In a time switch, a casing, a switch mechanism in said casing, meanscarrying said mechanism in a path about an axis, said mechanismincluding a make and break element, means for shifting said element fromone position to another, said shifting means including a set of rockinglevers, a device having means to engage said rocking levers to actuatesaid make and break element alternately to open and close the switch,and manually operated means to set said rocking levers to be engaged bysaid engaging means, said engaging device including a jagged wheeldisposed concentrically to said rocking levers, the number of teeth onsaid jagged wheel being the same as'the number of rocking'leversprovided.

18. In a time switch, a casing, a power applying mechanism housed bysaid casing, a switch mechanism within the casing for opening andclosing an electrical' circuit, and ,including a movable contactcontrolling member, elements in the casing for eilecting actuation ofsaid controlling member when said elements are set to their operativepositions, a rotatable ringy carried by the casing, means carried by thering and brought into operative relation with a selected element byturning the ring, for setting the said selected element to its operativeposition, and means affected by said movable ccntact-ccntroliing'memberfor indicating the ccndition of said switching mechanism.

KARL maENEDEa.

